[fumiya]

I've attached a simplified energy transport simulation case for incompressible flow with the following functionality in OpenFOAM v2006:

• energyTransport: to solve a simplified energy transport equation
• readFields: to read kappa value to be able to use externalWallHeatFluxTemperature boundary condition
• externalWallHeatFluxTemperature: to set heat flux boundary condition

Settings of readFields and energyTransport function objects in system/controlDict

    readKappaFields
    {
        type        readFields;
        libs        (fieldFunctionObjects);

        fields      (kappaField);

        readOnStart true;
    }

    energyTransport
    {
        type            energyTransport;
        libs             (solverFunctionObjects);

        enabled         true;
        writeControl    outputTime;
        writeInterval   1;

        field           T;
        phi             phi;

        // Thermal properties
        Cp              Cp    [J/kg/K]  1e3;
        kappa           kappa [W/m/K]   0.0257;
        rhoInf          rho   [kg/m^3]  1.2;

        write           true;

        fvOptions
        {
        }
    }

Settings of heat flux boundary condition(q=500[W/m^2]) in 0.orig/T

    hole
    {
        type            externalWallHeatFluxTemperature;
        mode            flux;
        q               uniform 500;
        kappaMethod     lookup;
        kappa           kappaField;
        value           uniform 300;
    }

where kappa value is read from 0.orig/kappaField

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2006                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      kappaField;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 1 -3 -1 0 0 0];

internalField   uniform 0.0257;

boundaryField
{
    inlet
    {
        type             fixedValue;
        value            $internalField;
    }

    outlet
    {
        type             fixedValue;
        value            $internalField;
    }

    up
    {
        type            symmetry;
    }

    hole
    {
        type             fixedValue;
        value            $internalField;
    }

    frontAndBack
    {
        type            empty;
    }
}

Hope this helps,
Fumiya